The genetic inheritance of glaucoma is still unclear. However, a family history of glaucoma has been found in up to 50% of patients with the most common type of glaucoma, known as primary open-angle glaucoma. One type of glaucoma occurs in people who have had a history of being hit in the eye (e.g. soccer ball). Not only can they get a rise in pressure initially after the injury, but they also may develop glaucoma years later. All of these things stress the importance of regular eye exams.